This invention relates to a method for the production of synthesis gas, and in particular to a method of producing synthesis gas from coal.
Synthesis gas is a mixture of carbon monoxide and hydrogen. Depending on the production method, the ratio CO:H2 varies from 1:1 to 1:3. Depending on the type of coal used and the conversion type (by water steam or nonstoichiometric quantity of 02), the ratio of components in the gas mixture varies broadly:

These ratios are also determined by the coal gasification method and conditions. The commonly used Lurgi method produces the following raw gas ratios: 15-18% CO, 38-40% H2, 9-11% CH4, 30-32% CO2. With temperature increase the CO share increases; with pressure increase, H2 and CH4 increase. Impurities may include inert gases (N2, etc.) and H2S, if the raw material contained sulfur. Synthesis gas is cleaned from H2S and CO2 by selective solvents; CO and H2 ratio is regulated, when required, converting carbon oxide by water steam.
In the present invention the coal used must be conditioned. Several coal conditioning methods are used. Coal in anthracite form is cut to produce cylindrical rods, ⅝″ in dia. and 7″ long. Each cylindrical rod is sintered in an oven. The coal is sintered at a typical temperature range from 670 to 1050° C., with no air, for 10-14 hours. The temperature may be even higher than this range. The coal sintering temperature (charred coal or partially carbonized coal) is chosen for specific conditions of the synthesis gas.
Another conditioning method uses different types of coal crushed to duct and mixed in different ratios with the fillers, such as: iron, calcium or electric-furnace scrap or open-hearth slag, depending on the desired final gas composition. Temperature impacts remove volatile fractions of resins that can be fractionally distilled to produce targeted fractions.
The combustible coal element is believed to be conditioned as soon as conducts the electric current uniformly in the entire coal fraction.
A catalyst for the coal combustion reaction may be provided. Catalytic gasification processes, based on the direct coal conversion to gaseous compounds, are well known in the prior art. For efficient catalyst impact, the catalyst should have a good contact with hard raw material. To this end, catalysts used are deposited on the coal surface so they can be melted or sublimed in the process, thus getting into pores of the coal. The most common catalysts for coal gasification are compounds of alkali, alkaline-earth and some transition metals (Ni, Fe, Co), able to catalyze CO and hydrocarbon conversion oxidation reaction, methanation. Such catalytically active materials can be used in the process of gasification until they fully wear off at combustion temperatures 850-1400° C. under atmospheric pressure.
In a steam-and-air mixture, the coal conversion to gaseous products may exceed 90%. The gasification intensity exceeds the known gasification technology indicators, under similar temperature and pressure.
In order to ensure a good contact with coal, the following is required. Thermally-processed coal (charred coal or partially carbonized coal) should be impregnated with acetic acid containing dissolved substances based on iron, magnesium and manganese oxides, or molybdenum, chromium or nickel. In particular, metallic iron, ammonium molybdate (NH 4)6 Mo 7 and chromium oxide CrO, potassium permanganate KMnO4 are dissolved in specific ratios, depending on the required final gas composition. The coal element saturated with this solution is dried at 90° C. The combustible coal element is tightly packed by galvanic or other techniques in a cylindrical case, made from alloys: natural pyrite, Fe2O3 or synthetic FeS2, or compounds of Fe, cobalt Co, nickel Ni, or molybdenum Mo, the compounds deposited on Al2O3. In turn, they are electrical conductors and reaction catalysts. Reaction catalysts can also include acid clays, such as kaolin Al2O3*2SiO2*2H2O or similar clays.